Enter data into a cell have comment generated with the current date and time

In a worksheet i use cells from B3:B22toG3:G22(bcdef...) but i don't fill all the data in one time.
It is necessary that when i enter the data into a cell, a comment would be generated with the current date and text(text would be nice, but not realy necessary). For example "the customer was registered: 2011.12.05" the date has to remain static.
Is there any way to do it? I tried some things with macros, but i'm starting to give up.

thank you in advance, and sorry for my english.